Plant based diet - are you meeting your nutritional requirements?
A vegan diet includes foods from plant sources only. It can be nourishing and satisfying, but it takes very careful planning to avoid nutritional deficiencies. Vegans must work hard to ensure they are consuming adequate amounts of essential fatty acids, protein, Vitamin B12, Vitamin D, iron, zinc and calcium. There are millions of vegans in the world, including elite athletes such as Carl Lewis and Venus Williams who have competed at international level while consuming no animal products. You should have a regular annual blood test to check your levels of vitamin B12, vitamin D and iron.
Essential fatty acids
Some organisations (especially those who promote consumption of animal products) suggest that a vegan diet is deficient in essential fatty acids. This is common but not necessarily true. The recommendations for EFA are currently 4g of omega 3 and 12g of omega 6 fatty acids. This can be achieved by including 30g walnuts to your diet, alternatively adding 1 tbsp of flaxseed oil every day, either as a salad dressing, stirred into breakfast cereal, or straight off the spoon.
It was previously thought that complete proteins needed to be consumed at each meal, so vegans ensured they mixed grains and legumes to obtain complete protein. Research now suggests that complementary proteins (the right combination of legumes, nuts and grains) need to be consumed during the same day rather than the same meal.
According to the vegan society of the UK, vegans must supplement their diet with Vitamin B12 tablets or fortified foods. The Vitamin B12 in seaweeds, spirulina, tempeh and barley grass is not absorbed into the bloodstream and so is not an adequate source of this nutrient. Warning signs of low Vitamin B12 are tingling of fingers, toes and tongue. Longer term deficiency causes anaemia, deterioration in mental functioning and possibly heart disease. A diet high in folic acid (such as a vegan diet) may prevent the changes in red blood cells but not the nerve damage or deterioration in mental functioning. Vitamin B12 deficiency is life threatening for a developing foetus and baby, so it is vitally important that a vegan diet be supplemented with Vitamin B12 during pregnancy and breastfeeding.
Dietary Vitamin D is only available in animal foods (fish, fish liver, beef liver, eggs), so a vegan diet will be deficient in dietary vitamin D. It is quite possible to obtain adequate Vitamin D from moderate sun exposure. The following recommendations come from the Sydney Melanoma Diagnostic Centre at RPA Hospital:
The amount of sun exposure required to get adequate vitamin D levels depends on skin type (the fairer your skin the less you need), age (more time in the elderly), latitude, season, time of the day and cloud cover. Daily exposure to as little as one-third of a sunburning dose to 15% of your body surface (hands, arms and face; or legs) can produce significant amounts of vitamin D. For fair skin people (those that tend to burn rather than tan) this can be achieved around 6-8 minutes just before 10am or just after 2pm (standard time) in summer in most of Australia but in winter takes around 30-50 minutes in southern parts of Australia.
Iron is plentiful in plant foods and is more easily absorbed if you combine the foods with Vitamin C. You need to consume 15mg daily (for men or post menopausal women) and 20-30 mg daily (for premenopausal woman). These levels are higher than for meat eaters as iron from meat is more readily absorbed.
|Food||Serving size||mg iron|
|Kidney beans||½ cup, cooked||3|
|Lentils||½ cup, cooked||3|
|Spinach||½ cup, cooked||3|
|Quinoa||½ cup, cooked||3|
|Potato with skin||1 medium baked potato||3|
|Cashew nuts||¼ cup||2|
The recommended daily intake for zinc is 3mg daily for 0-3 years, 5mg daily for 4-8 years, 8mg daily for all people over the age of 8, and up to 12mg daily during pregnancy and breastfeeding.
|Food||Serving size||mg zinc|
|Pumpkin seeds||½ cup||8|
|Sunflower seeds||½ cup||4|
|Chickpeas||½ cup, cooked||1|
The recommended daily intake for calcium is 210mg for babies aged up to 6 months, 270mg for 7-12 months, 500mg for 1-3 years, 800mg for 4-8 years, 1300mg for 9-18 years, 1000mg for 19-50 years and 1200mg after 50 years of age. High animal protein intake causes increased urinary calcium losses, and these RDIs are for the average Australian, who consumes most of their protein from animal sources.
|Food||Serving size||mg calcium|
|Tofu, calcium set||½ cup||250|
|Chinese cabbage||½ cup, cooked||250|
|Rhubarb||½ cup cooked||175|
|Spinach||½ cup cooked||100|
|Bok choy||½ cup, cooked||80|
|Kale||½ cup, cooked||60|
|Dried figs||4 figs (30g)||50mg|
|Broccoli||½ cup, cooked||35|